1. Field of the Invention
The present invention relates to an indicator panel having an inkjet design film on a resin substrate, and a method of manufacturing the indicator panel.
2. Description of Related Art
Conventionally, an indicator device, e.g., an instrument panel, is provided in a vehicle. Generally, the indicator device includes a panel and a light source. The panel includes a design portion having scales and letters, and the light source is provided at a backside of the panel. In the panel, the design portion except for the scales and the letters is made of an opaquex portion, in which a light is not transmitted. The scales and the letters are made of a translucent portion, in which a light is transmitted. Thereby, the translucent portion, e.g., the scales and the letters, can be displayed clearly by illuminating the panel with the light source at night. Moreover, because a high-quality appearance, visibility and texture are required for the instrument panel, e.g., automobile meter panel, the panel is thermoformed in a stereoscopic shape.
The indicator panel is usually manufactured by printing the opaque portion (solid concealing image portion) on a surface of a transparent substrate made of resin, e.g., polycarbonate, in a screen-printing. The screen-printing is a printing method, in which ink is printed on a substrate through a screen after an image from print data is drawn on the screen. The screen-printing has an advantage that a dark opaque portion can be printed at one time.
Further, in the screen-printing, a solvent drying type ink or heat hardening type ink is mainly used. Because the screen-printing is a monochromatic printing, multilayer printings using different color inks are required for forming a multicolored design. In this case, a process number and a process time for the screen-printing are increased. Furthermore, in the screen-printing, a design is restricted because an accuracy of a printing position and a resolution are generally low.
JP-U-60-159319 and JP-A-8-21749 disclose a stereoscopic indicator panel for the automobile meter panel, in which a predetermined part, e.g., dial, is protruded from the other part by a thermal drawing process, e.g., pressing process. However, a strict deforming control is required, because an accuracy defect and a variation in brightness are generated due to a slight displacement. Therefore, a time and a cost for the manufacturing are increased, because a number of formings and testings of the screens are needed for positioning adjustments.
Except for the screen-printing, a digital printing method such as a laser printing, an electrophotography printing, a thermoelectric printing and an inkjet printing is used in other fields, e.g., office automation printer field. These printings can perform a direct printing on the resin substrate without forming the screen. Thus, these printings may be better for a small lot printing than the screen-printing.
Among the digital printing methods, the inkjet printing rapidly becomes common in the office automation printer field, because the initial cost is low and the resolution is high due to a simple structure. The inkjet printing is performed by jetting ink from a computerized head nozzle.
JP-A-2002-156252 discloses an indicator panel for a display device, in which the panel is formed by the inkjet printing on a translucent substrate made of resin. U.S. Pat. No. 6,856,478 (corresponding to JP-2004-A-286459) discloses an indicator panel, in which an ink receiving layer and a light shielding printed layer are laminated on a substrate by the inkjet printing. The indicator panel formed by the inkjet printing has a high resolution such that a sharp and clear design can be formed on the panel. Thus, the indicator panel having a high-quality design can be manufactured.
However, when the indicator panel having an ink film produced by the inkjet printing is further thermoformed so as to be shaped, the high-quality design with the inkjet printing may be easily damaged. For example, a crack and a removal of the ink film are generated. Therefore, the thermoformed indicator panel may not practically used.